Turkey and the US President Trump’s decision to arm the Kurdish forces in Syria.

US President Trump has approved a plan to directly arm Kurdish forces fighting in Syria, the Pentagon said on Tuesday, the 9th of May inflaming already strained ties with Turkey and putting the U.S. military a step closer to seizing a remaining Islamic State stronghold.

The decision, which was first reported by NBC, is sure to enrage Turkey, which views the Kurdish People’s Protection Units (YPG), which make up the largest share of the SDF, as an existential threat. According to the WashingtonPost, “the Trump administration — nor the Barack Obama administration before it — had not made any secret of its intention to give the Syrian Kurds a primary role in attempting to seize Raqqa. Defense officials have said repeatedly the Raqqa operation would require direct weapons shipments and upgraded equipment as local forces maneuver though minefields and other obstacles leading into the city.”

The militant group, the People’s Protection Units, known by the Kurdish abbreviation Y.P.G., is fighting alongside Syrian Arab forces against the Islamic State and is intending to expel the jihadist organization from its de facto capital in Raqqa, Syria. But Turkey considers the Y.P.G. a terrorist organization and asserts that it is closely linked to the P.K.K., a Kurdish separatist group that has waged an insurgency against the Turkish government.

Last year the Turkish leader moved military forces into northern Syria, ostensibly to fight against the Islamic State, but equally to ensure that YPG forces did not consolidate along Turkey’s southern border. More recently, Erdogan has suggested he would send Turkish troops deeper into Syria, toward Raqqa, despite American plans to support a Kurdish-dominated offensive.

According to Reuters, Turkey warned the United States on Wednesday that a decision to arm Kurdish forces fighting Islamic State in Syria could end up hurting Washington, and accused its NATO ally of siding with terrorists.

The rebuke came a week before President Tayyip Erdogan is due in Washington for his first meeting with U.S. President Donald Trump, who approved the arms supply to support a campaign to retake the Syrian city of Raqqa from Islamic State.

The United States regards the YPG as a valuable partner in the fight against Islamic State militants in northern Syria. Washington says that arming the Kurdish forces is necessary to recapturing Raqqa, Islamic State’s de facto capital in Syria and a hub for planning attacks against the West.

That argument holds little sway with Ankara, which worries that advances by the YPG in northern Syria could inflame the PKK insurgency on Turkish soil.

Weapons supplied to the YPG have in the past fallen into PKK hands, said Turkish Foreign Minister Mevlut Cavusoglu.

While Turkey could impose limits on the use of the Incirlik base, that would hamper operations against Islamic State, which also menaces Turkey itself and has claimed responsibility for attacks including the bombing of Istanbul airport.

Turkey could also step up air strikes on PKK targets in northern Iraq. Turkish warplanes attacked Kurdish YPG fighters in northeastern Syria and Iraq’s Sinjar region late last month.

Turkey has consistently warned that it could intervene militarily in the region. But the prevailing view was that Turkey refrained from military action so as not to confront the United States and Russia. That restraint ended April 25 when Turkish jets bombed YPG facilities at Mount Karachok, near the Syrian town of Derik, and Kurdistan Workers Party (PKK) targets near Iraq’s Sinjar.

The Economist reports that while America complains that Turkey is bombing its proxies, Turkey fumes that America is arming its enemies. Over the past couple of years, a relentless cycle of PKK attacks and brutal military reprisals has left a trail of destruction, displacement, and thousands of victims across Turkey’s Kurdish south-east.

For Barin Kayaoglu columnist for Al-Monitor, now, the million-dollar question is whether Ankara will make any moves to weaken the YPG-SDF offensive (as it did with the April 25 airstrikes), or wait out the United States, which has a habit of prematurely withdrawing from Middle Eastern conflicts and a history of abandoning Kurds?